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Date: Thu, 22 Dec 2022 13:46:57 -0800 From: Joanne Koong <joannelkoong@...il.com> To: Paolo Abeni <pabeni@...hat.com> Cc: Kuniyuki Iwashima <kuniyu@...zon.com>, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Jiri Slaby <jirislaby@...nel.org>, Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org Subject: Re: [PATCH RFC net 1/2] tcp: Add TIME_WAIT sockets in bhash2. On Thu, Dec 22, 2022 at 7:06 AM Paolo Abeni <pabeni@...hat.com> wrote: > > On Thu, 2022-12-22 at 00:12 +0900, Kuniyuki Iwashima wrote: > > Jiri Slaby reported regression of bind() with a simple repro. [0] > > > > The repro creates a TIME_WAIT socket and tries to bind() a new socket > > with the same local address and port. Before commit 28044fc1d495 ("net: > > Add a bhash2 table hashed by port and address"), the bind() failed with > > -EADDRINUSE, but now it succeeds. > > > > The cited commit should have put TIME_WAIT sockets into bhash2; otherwise, > > inet_bhash2_conflict() misses TIME_WAIT sockets when validating bind() > > requests if the address is not a wildcard one. (resending my reply because it wasn't in plaintext mode) Thanks for adding this! I hadn't realized TIME_WAIT sockets also are considered when checking against inet bind conflicts. > > How does keeping the timewait sockets inside bhash2 affect the bind > loopup performance? I fear that could defeat completely the goal of > 28044fc1d495, on quite busy server we could have quite a bit of tw with > the same address/port. If so, we could even consider reverting > 28044fc1d495. > Can you clarify what you mean by bind loopup? > > [0]: https://lore.kernel.org/netdev/6b971a4e-c7d8-411e-1f92-fda29b5b2fb9@kernel.org/ > > > > Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address") > > Reported-by: Jiri Slaby <jirislaby@...nel.org> > > Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com> > > --- > > include/net/inet_timewait_sock.h | 2 ++ > > include/net/sock.h | 5 +++-- > > net/ipv4/inet_hashtables.c | 5 +++-- > > net/ipv4/inet_timewait_sock.c | 31 +++++++++++++++++++++++++++++-- > > 4 files changed, 37 insertions(+), 6 deletions(-) > > > > diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h > > index 5b47545f22d3..c46ed239ad9a 100644 > > --- a/include/net/inet_timewait_sock.h > > +++ b/include/net/inet_timewait_sock.h > > @@ -44,6 +44,7 @@ struct inet_timewait_sock { > > #define tw_bound_dev_if __tw_common.skc_bound_dev_if > > #define tw_node __tw_common.skc_nulls_node > > #define tw_bind_node __tw_common.skc_bind_node > > +#define tw_bind2_node __tw_common.skc_bind2_node > > #define tw_refcnt __tw_common.skc_refcnt > > #define tw_hash __tw_common.skc_hash > > #define tw_prot __tw_common.skc_prot > > @@ -73,6 +74,7 @@ struct inet_timewait_sock { > > u32 tw_priority; > > struct timer_list tw_timer; > > struct inet_bind_bucket *tw_tb; > > + struct inet_bind2_bucket *tw_tb2; > > }; > > #define tw_tclass tw_tos > > > > diff --git a/include/net/sock.h b/include/net/sock.h > > index dcd72e6285b2..aaec985c1b5b 100644 > > --- a/include/net/sock.h > > +++ b/include/net/sock.h > > @@ -156,6 +156,7 @@ typedef __u64 __bitwise __addrpair; > > * @skc_tw_rcv_nxt: (aka tw_rcv_nxt) TCP window next expected seq number > > * [union with @skc_incoming_cpu] > > * @skc_refcnt: reference count > > + * @skc_bind2_node: bind node in the bhash2 table > > * > > * This is the minimal network layer representation of sockets, the header > > * for struct sock and struct inet_timewait_sock. > > @@ -241,6 +242,7 @@ struct sock_common { > > u32 skc_window_clamp; > > u32 skc_tw_snd_nxt; /* struct tcp_timewait_sock */ > > }; > > + struct hlist_node skc_bind2_node; > > I *think* it would be better adding a tw_bind2_node field to the > inet_timewait_sock struct, so that we leave unmodified the request > socket and we don't change the struct sock binary layout. That could > affect performances moving hot fields on different cachelines. > +1. The rest of this patch LGTM. > > Thanks, > > Paolo >
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